The invention concerns a semiconductor diode having three adjacent regions: two that are doped in the same manner, and a third that is doped oppositely from the other two regions and that separates them. The two regions that are doped in the same manner have ohmic contacts.
A semiconductor diode of this kind has an NPN or PNP structure consisting of three adjacent semiconductor layers with ohmic contacts. To reduce the energy barriers, the width of the middle layer in the three layer structure is made thin enough so that even without external voltage being applied to the electrodes, with the given doping of this layer, the entire area of this laver is depleted of free charge carriers. Diodes of the n+p or p+n type can be adapted only with difficulty, if at all, for use as protective diodes for gallium arsenide components, the more so as for this purpose high p-dopings would have to be introduced in gallium arsenide, which is known to be difficult or impossible. On the other hand, gallium arsenide components that are manufactured on semi-insulating substrates are very sensitive to static discharge. For this reason, no protective diodes made of connecting semiconductors have been installed on semi-insulating substrates. Due to the sensitivity of gallium arsenide components to static discharges and to the fact that components of this kind are designed primarily as planar components on a semi-insulating substrate, a concept for manufacturing planar protective diodes for gallium arsenide components on semi-insulated substrates would be of particular importance.
It is therefore one purpose of this invention to provide a semiconductor diode that is suited for use as a planar diode on semi-insulating substrates as well as other ones, and which has an arbitrarily small threshold voltage, so that it can be used, for example, as a protectIve diode for other semiconductor components located on the substrate.